From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80BCCC4332F for ; Tue, 15 Nov 2022 17:00:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230393AbiKORAB (ORCPT ); Tue, 15 Nov 2022 12:00:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229767AbiKORAA (ORCPT ); Tue, 15 Nov 2022 12:00:00 -0500 Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4039228716 for ; Tue, 15 Nov 2022 08:59:58 -0800 (PST) Received: by mail-wr1-x435.google.com with SMTP id y16so25333976wrt.12 for ; Tue, 15 Nov 2022 08:59:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:message-id:in-reply-to:date :subject:cc:to:from:user-agent:references:from:to:cc:subject:date :message-id:reply-to; bh=mfMmr+1QjnU4sjisGoRqb8FxQFwgEIl76i25CgDhNpM=; b=UqienqYRbAH1e7sBF3xN1GzQ8JdfuqdaWqFqMP035H8CJyl9AAUJSxwUBiO+qV+wS1 j2+sEBQeEWUhhlE8ZdvRf+ZiZC11E+JtnjQBGWqt55TQ5ojF5av0xQ0wfwww8/QCcLo0 8GOkGU4WQOpSOHyF0SkAkiHP6h0Lo/Q1bpP2Z9TsjHOP6LPgvrNrPFpIHdVDwAiZGv1s bXYcK28rMaUtSlGU+/1U6fOi4/tj6/fZgiRiWt3pEHmgs6vbP27mioTyX1gaSyGeAhJP E73h2QDDCPNlZZoOl/dZq2jCFsoI3nF/FCoeBB/4o1ai7DAKHVm5TRu75uSL+hb9Nzkz xouQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:in-reply-to:date :subject:cc:to:from:user-agent:references:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=mfMmr+1QjnU4sjisGoRqb8FxQFwgEIl76i25CgDhNpM=; b=dG9Oy0HQxgEnaYHRZtdam2sD9/e6pe/WfMKjrOIrZhVCOFKVCGP2yY/vDhyvrQmLiT JQ99+d0vWdO6cyE8i26q7TwjpsLPflMlhU3hcLiBafsdZhu5ap00guBz0tS0mmzfCZww u+sVR+Oiojpz49eIyIM8Ksw0k9ukkXnlQ3iYXC+/f3Gy5IjLtRlKnRUxGzXxhTjOHzmo HSedw7+mwZj1fFNZ1LGZYLFL2z5bRz5NQXXTlX/iiX/V/yZvQ60BNwhkMDQb9a3IcWnM VY+XF+RXPrB4LY9tVE76WNtmrMtpw9hkyL9BBMLFTJ3ipaQSKTjORG7BHwsn0L1NBJzV +lew== X-Gm-Message-State: ANoB5plyILFLGD4SPtJhjpCsnasliHU2vZUa6OLbX0AsAYhssPIR+MAo 9lqbkPTQ0KwNh/+B0a0P6apKtQ== X-Google-Smtp-Source: AA0mqf5UAnWqAlfsUVaCZun0Qjg6m/flblOYFMgHrRCoRvoR77BrSCG7B6qCWFEvqij78GTSI8YGew== X-Received: by 2002:a5d:6743:0:b0:22e:28fe:39d6 with SMTP id l3-20020a5d6743000000b0022e28fe39d6mr11543050wrw.701.1668531596730; Tue, 15 Nov 2022 08:59:56 -0800 (PST) Received: from zen.linaroharston ([185.81.254.11]) by smtp.gmail.com with ESMTPSA id bl21-20020adfe255000000b002366dd0e030sm12793968wrb.68.2022.11.15.08.59.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Nov 2022 08:59:55 -0800 (PST) Received: from zen (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id 5BEF21FFB7; Tue, 15 Nov 2022 16:59:55 +0000 (GMT) References: <20221025151344.3784230-1-chao.p.peng@linux.intel.com> <20221025151344.3784230-4-chao.p.peng@linux.intel.com> User-agent: mu4e 1.9.2; emacs 28.2.50 From: Alex =?utf-8?Q?Benn=C3=A9e?= To: Chao Peng Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , tabba@google.com, Michael Roth , mhocko@suse.com, Muchun Song , wei.w.wang@intel.com Subject: Re: [PATCH v9 3/8] KVM: Add KVM_EXIT_MEMORY_FAULT exit Date: Tue, 15 Nov 2022 16:56:12 +0000 In-reply-to: <20221025151344.3784230-4-chao.p.peng@linux.intel.com> Message-ID: <87cz9o9mr8.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org Chao Peng writes: > This new KVM exit allows userspace to handle memory-related errors. It > indicates an error happens in KVM at guest memory range [gpa, gpa+size). > The flags includes additional information for userspace to handle the > error. Currently bit 0 is defined as 'private memory' where '1' > indicates error happens due to private memory access and '0' indicates > error happens due to shared memory access. > > When private memory is enabled, this new exit will be used for KVM to > exit to userspace for shared <-> private memory conversion in memory > encryption usage. In such usage, typically there are two kind of memory > conversions: > - explicit conversion: happens when guest explicitly calls into KVM > to map a range (as private or shared), KVM then exits to userspace > to perform the map/unmap operations. > - implicit conversion: happens in KVM page fault handler where KVM > exits to userspace for an implicit conversion when the page is in a > different state than requested (private or shared). > > Suggested-by: Sean Christopherson > Co-developed-by: Yu Zhang > Signed-off-by: Yu Zhang > Signed-off-by: Chao Peng > --- > Documentation/virt/kvm/api.rst | 23 +++++++++++++++++++++++ > include/uapi/linux/kvm.h | 9 +++++++++ > 2 files changed, 32 insertions(+) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.= rst > index f3fa75649a78..975688912b8c 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -6537,6 +6537,29 @@ array field represents return values. The userspac= e should update the return > values of SBI call before resuming the VCPU. For more details on RISC-V = SBI > spec refer, https://github.com/riscv/riscv-sbi-doc. >=20=20 > +:: > + > + /* KVM_EXIT_MEMORY_FAULT */ > + struct { > + #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1 << 0) > + __u32 flags; > + __u32 padding; > + __u64 gpa; > + __u64 size; > + } memory; > + > +If exit reason is KVM_EXIT_MEMORY_FAULT then it indicates that the VCPU = has > +encountered a memory error which is not handled by KVM kernel module and > +userspace may choose to handle it. The 'flags' field indicates the memory > +properties of the exit. > + > + - KVM_MEMORY_EXIT_FLAG_PRIVATE - indicates the memory error is caused by > + private memory access when the bit is set. Otherwise the memory error= is > + caused by shared memory access when the bit is clear. What does a shared memory access failure entail? If you envision any other failure modes it might be worth making it explicit with additional flags. I also wonder if a bitmask makes sense if there can only be one reason for a failure? Maybe all that is needed is a reason enum? > + > +'gpa' and 'size' indicate the memory range the error occurs at. The user= space > +may handle the error and return to KVM to retry the previous memory acce= ss. > + > :: >=20=20 > /* KVM_EXIT_NOTIFY */ > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index f1ae45c10c94..fa60b032a405 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -300,6 +300,7 @@ struct kvm_xen_exit { > #define KVM_EXIT_RISCV_SBI 35 > #define KVM_EXIT_RISCV_CSR 36 > #define KVM_EXIT_NOTIFY 37 > +#define KVM_EXIT_MEMORY_FAULT 38 >=20=20 > /* For KVM_EXIT_INTERNAL_ERROR */ > /* Emulate instruction failed. */ > @@ -538,6 +539,14 @@ struct kvm_run { > #define KVM_NOTIFY_CONTEXT_INVALID (1 << 0) > __u32 flags; > } notify; > + /* KVM_EXIT_MEMORY_FAULT */ > + struct { > +#define KVM_MEMORY_EXIT_FLAG_PRIVATE (1 << 0) > + __u32 flags; > + __u32 padding; > + __u64 gpa; > + __u64 size; > + } memory; > /* Fix the size of the union. */ > char padding[256]; > }; --=20 Alex Benn=C3=A9e